Ventilation in summer without controlled residential ventilation is problematic

Leave the windows closed during the day. Still ventilate early in the morning and in the evening; 14 degrees and 80 percent humidity outside is still drier than 22 degrees with 58 percent inside. Ventilating makes your indoor air drier. Even if that is hard to believe....

The problem right now, however, is that outside it is at least around 18 degrees at night for at least a week. Then the calculation doesn’t add up, as the temperature difference is too small. Still ventilate? According to the app, no. I don’t know how quickly it becomes critical, but not ventilating for a week is also stupid.

I don't know how quickly it becomes critical, but not ventilating for a week is stupid too.

Seriously?
You want to not ventilate for a week because an app tells you to?

Just let the numbers be numbers and ventilate with common sense.
Or do you think the other 80 million people in Germany have some secret trick for ventilating?
How have you ventilated so far?

Besides, it's not just about the humidity, the CO2 has to get out too.

PS: Just buy a dehumidifier, then you can also ventilate in summer with a clear conscience.

You are probably right. I have a dehumidifier, but it does little in a relatively large house.

And just because you have an indoor humidity of 65 percent for a week doesn't mean there is mold. It is relatively warm for that. In [Winter] it would be more problematic

Do you have a basement apartment now? I would actually ventilate a utility cellar very sparsely in the summer, possibly additionally dehumidify.

And regarding the house: In summer the air inside is simply more humid, without air conditioning you won’t be able to do much about it.